Method for treating bronze wastes for recovering copper, tin, lead, and precious metals therefrom



an industrial Patented Oct. 8, 1935 2,016,718 METHOD FOR TREATING BRONZE WASTES FOR RECOVEBING: COPPER, AND PRECIOUS METALS TIN. LEAD,

Auguste Bollard, Paris, France Drawing.

Serial No. 578,224. 1930 This invention relates to a method for treating bronze wastes for recovering copper. tin-.l a and precious metals thereirom. The main object of method for through electrolysis in order the invention is to.provide treating bronze wastes to recover copper,

tin, lead and other precious metals contained in the'same and to separate them from the sludge formed during the electrolysis.

. Separation of comma-I do not use smolten bronze anodes because they lead to a progressive impoverishment oi the electrolytic bath in copper and I recommend anodes formed of granulated bronze pressed phragms and through which and steam; said turnings or between two diapasses a flow 01 air flow facilitating the dissolution oi the bronze wastes and heating the bath, maintaining it in a suitable circulating condition.

Each of these diaphragms is grids-0r any other formed oi two lead resistant -metal-(storage battery grids are most suitable for this purpose) applied against each other, but separated. from each other by a sheet oi wool (such as ior instance a piece oi flannel).

V The electrolysis vat, which may be of wood and the section of which may be a rectangular one, receives said diaphragm. the edges of which are fitted in the bottom and sides of the vat, respectively. Said diaphragms are located at equal distances (a few centimeters) from each .other'and divide themat into a number of compartments. The odd compartments receive the bronze wastes and form all connected in parallel.

the anodes The even compartwhich are m'ents receive the cathodes which are all connected in parallel, each cathode being iormcd of a copper sheet which .may frame. at the'ends or the vat In order to reduce befitted'inaninsulating Provision is made for the compartments to be anodic compartments.

the amount of electric'energy given out, the anodic compartments may also be connected in series. The

prise a first anodic compartment situated filled with. bronze .wastes main-- er'l oi ,the vat tained between the outermost will then comat one vat wall of the val; and

- a first diaphragm (double grid. flannel); to this firstcompartment follows a second one filled with electrolyte and limited lytic copper will settle.

V This cathode forms one of compartment which is an anodic by aleadcathode (or o! any other resistant metal), on whichthe electroewansorrms compartment fllled with bronze wastes, the other wall or this compartment being a diaphragm (double grid,

flannel) limitin No.4 comp the electrolyte, and so on.

artment filled with temper bottom'oi the vat. To

7 water. PM

' it, whereaiter the wastes. The sludge which is insoluble lay-washing Application November so, 1931, In France December '1,

ior instance copper sulphate (150 grams 0! said salt in a crystallized condition per liter) and of sulphuric acid (100 grams per liter). Thus, the anodes and the cathode are immersed in said solution which is heated by the steam flowing through the compartments and brought to a ature which may vary. for instance between 30 and 60 C.

when such temperature is reachedsteam ad'- dition is usually no more necessary, the temperature being maintained by the passage of the electric current and 0! the air.

The copper precipitates into the cathode in a clean and thick coating under a density 01 cur- 15 rent of 2 to 3 amperes per square decime'ter of the cathode.

The bath tends to grow poorer in sulphuric acid and such an acid is added to the bath either periodicaily or continuously. If the concentration of 20 the bath in copper sulphate has a tendency to become greater, the addition oi air will be diminished.

Sludge treatment.-Thebronze wastes in the anodic compartments are washed from time to 5 time with water, through which the sludge accompanying the wastes is caused to sink into the this end the vat is first emptied, then the sludge, carried away with the tom of each compartment and having its bung taken out for this purpose. U The sludge-is washed outwith water and deprived of all copper sulphate which accompanies it is dried and then passed through 35 a sieve (No. -100). The pieces remaining 'on the sieve are treated anew electrolytically with is roasted at a temperature not exceeding 200 to 300 0., as otherwise the copper might be converted into co per protoxide 40 in diluted sulphuric acid and silver might be converted into silver oxide which is soluble in the same acid. Aiter said roastin the sludge is treated by diluted and hot sulphuricacid, for instance 35 liters of sulphuric acid of 66 5 B. and 350 liters of water for kilos of dry sludge. A liquid is thus obtained in which copper sulphate crystallizes in a cold condition. The sulphate which still adheres to the sludge is sepdissolves the sulphate and the poor copper solutionthus obtained is used for subsequent treatments.

The sludge extracted and deprived of its copper sulphate is roasted anew in the same condi-' 55 through a hole provided in the bot- 30 the sludge with water which 50 very small quantity of copper sulphate is obtained. The residual sludge, which generally does not represent half 01' its original weight, is dried, ground and smelted with a mixture of rosin and smolten borax in the form oi. a powder. The rosin allows of a smelting at a. temperature which is much lower than the temperature required when using coal. For instance, 10 kilos of residual sludge are molten with 5 kilos rosin and 2,500 of borax and, optionally, with 2,500 kg. of fluorspar and 2,500 kilos of sodium chloride. The molten tin easily separates from its slag. The crude tin may be refined electrolytically, the anodic sludge containing all gold and silver, and also lead and bronze wastes.

I claim:

1. A method of treating bronze wastes comprising maintaining a mass of the bronze waste in a confined zone in an electrolytic bath consisting of an acidified solution of copper sulphate, maintaining a cathode in said bath, passing an electric current through said mass of bronze waste as an anode and through said bath to deposit copper on said cathode, passing a mixture of air and steam through the mass of bronze waste while in said bath, draining the bath, washing the anode formed of bronze wastes to remove the sludge formed therein, separating copper sulphate from the sludge by washing, drying and sitting the sludge, roasting the slime at a temperature of 200-300 C., treating the roasted slime with hot-dilute sulphuric acidto separate copper in 5 the form of copper sulphate, drying and pulverizing the residue, and fusing it with a mixture of resin and molten borax for obtaining 'tin.

- 2. A method of treating bronze wastes comprising maintaining a mass of the bronze waste in a confined zone in an electrolytic bath consisting of an acidified solution of copper sulphate, maintaining a cathode in said bath, passing an electric current through said mass of bronze waste as an anode and through said bath to deposit copper on said cathode, passing air and steam through the mass of bronze waste while in said bath, draining the bath, washing the anode formed of bronze wastes to remove the sludge 20 formed therein, separating copper sulphate from the sludge by washing, drying and sitting the sludge, roasting the slime at a temperature of ZOO-300 C., treating the roasted slime with hot dilute sulphuric acid to separate copper in the copper sulphate, drying and pulverizing the residue and fusing it with a mixture of resin and molten borax for obtaining tin, electrolytically refining the tin, and treating the sludge formed at the anode for the extraction of lead, silver and gold.

AUGUSTE HOLLARD. 

